1. Field of the Invention
The present invention relates to a leaf spring for supporting supply and take-up reels of a video tape cassette and more particularly, to a leaf spring which is able to maintain the rotational center of supply and take-up reels uniform so as to obtain the smooth rotation of reels.
2. Description of the Prior Art
In a conventional tape cassette as shown in FIGS. 1 and 2, a supply reel 3 and a take-up reel 4 are rotatably mounted within upper and lower housings 1 and 2, and the supply and take-up reels 3 and 4 are guided by guide ribs 5 and 6 provided in the lower housing 2. The reels 3 and 4 are also resiliently pressed on pointed upper ends 7 and 8 thereof by both ends of a leaf spring 9 which is fixed on the lower surface of the upper housing 1. Therefore, the tape cassette is loaded on a video tape cassette recorder, the reels 3 and 4 can be rotated upon the rotation of supply and take-up reel tables (not shown).
In such conventional tape cassette, since the leaf spring 9 is adapted to merely press resiliently the pointed upper ends 7 and 8 of the reels 3 and 4 with both ends thereof, there are many problems, for example, the reels 3 and 4 are rolled arbitrarily when the tape is travelling, as much as a gap between the edges of frames of the reels and the guide ribs 5 and 6 so that a friction occurs therebetween, thereby giving rise to a bad travelling of the tape.
Furthermore, the gap between the supply reel 3 and the guide rib 5 disposed on the supply side is different from the gap between the take-up reel 4 and the guide rib 6 on the take-up side. Therefore, the condition of the tape travelling becomes worse. Also, since the leaf spring has an arcuate lozenge shaped configuration with a wide portion at the center thereof and both ends thereof becoming gradually narrower so as to provide a proper tensional force as shown in FIG. 2. Therefore, in manufacturing, a large amount of waste pieces are inevitably produced from cutting materials so that the productivity becomes low and the cost becomes high.